diff options
| -rw-r--r-- | drivers/block/loop.c | 98 | ||||
| -rw-r--r-- | drivers/block/loop.h | 2 |
2 files changed, 97 insertions, 3 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 75db3b98ec2b..23376084a5cb 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -445,6 +445,90 @@ static int lo_req_flush(struct loop_device *lo, struct request *rq) return ret; } +static inline void handle_partial_read(struct loop_cmd *cmd, long bytes) +{ + if (bytes < 0 || (cmd->rq->cmd_flags & REQ_WRITE)) + return; + + if (unlikely(bytes < blk_rq_bytes(cmd->rq))) { + struct bio *bio = cmd->rq->bio; + + bio_advance(bio, bytes); + zero_fill_bio(bio); + } +} + +static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) +{ + struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); + struct request *rq = cmd->rq; + + handle_partial_read(cmd, ret); + + if (ret > 0) + ret = 0; + else if (ret < 0) + ret = -EIO; + + rq->errors = ret; + blk_mq_complete_request(rq); +} + +static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, + loff_t pos, bool rw) +{ + struct iov_iter iter; + struct bio_vec *bvec; + struct bio *bio = cmd->rq->bio; + struct file *file = lo->lo_backing_file; + int ret; + + /* nomerge for loop request queue */ + WARN_ON(cmd->rq->bio != cmd->rq->biotail); + + bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); + iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, + bio_segments(bio), blk_rq_bytes(cmd->rq)); + + cmd->iocb.ki_pos = pos; + cmd->iocb.ki_filp = file; + cmd->iocb.ki_complete = lo_rw_aio_complete; + cmd->iocb.ki_flags = IOCB_DIRECT; + + if (rw == WRITE) + ret = file->f_op->write_iter(&cmd->iocb, &iter); + else + ret = file->f_op->read_iter(&cmd->iocb, &iter); + + if (ret != -EIOCBQUEUED) + cmd->iocb.ki_complete(&cmd->iocb, ret, 0); + return 0; +} + + +static inline int lo_rw_simple(struct loop_device *lo, + struct request *rq, loff_t pos, bool rw) +{ + struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); + + if (cmd->use_aio) + return lo_rw_aio(lo, cmd, pos, rw); + + /* + * lo_write_simple and lo_read_simple should have been covered + * by io submit style function like lo_rw_aio(), one blocker + * is that lo_read_simple() need to call flush_dcache_page after + * the page is written from kernel, and it isn't easy to handle + * this in io submit style function which submits all segments + * of the req at one time. And direct read IO doesn't need to + * run flush_dcache_page(). + */ + if (rw == WRITE) + return lo_write_simple(lo, rq, pos); + else + return lo_read_simple(lo, rq, pos); +} + static int do_req_filebacked(struct loop_device *lo, struct request *rq) { loff_t pos; @@ -460,13 +544,13 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq) else if (lo->transfer) ret = lo_write_transfer(lo, rq, pos); else - ret = lo_write_simple(lo, rq, pos); + ret = lo_rw_simple(lo, rq, pos, WRITE); } else { if (lo->transfer) ret = lo_read_transfer(lo, rq, pos); else - ret = lo_read_simple(lo, rq, pos); + ret = lo_rw_simple(lo, rq, pos, READ); } return ret; @@ -1570,6 +1654,12 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, if (lo->lo_state != Lo_bound) return -EIO; + if (lo->use_dio && !(cmd->rq->cmd_flags & (REQ_FLUSH | + REQ_DISCARD))) + cmd->use_aio = true; + else + cmd->use_aio = false; + queue_kthread_work(&lo->worker, &cmd->work); return BLK_MQ_RQ_QUEUE_OK; @@ -1589,7 +1679,9 @@ static void loop_handle_cmd(struct loop_cmd *cmd) failed: if (ret) cmd->rq->errors = -EIO; - blk_mq_complete_request(cmd->rq); + /* complete non-aio request */ + if (!cmd->use_aio || ret) + blk_mq_complete_request(cmd->rq); } static void loop_queue_work(struct kthread_work *work) diff --git a/drivers/block/loop.h b/drivers/block/loop.h index d1de2217c09a..fb2237c73e61 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -69,6 +69,8 @@ struct loop_cmd { struct kthread_work work; struct request *rq; struct list_head list; + bool use_aio; /* use AIO interface to handle I/O */ + struct kiocb iocb; }; /* Support for loadable transfer modules */ |